The reasons for my recommendations are several fold.
First and foremost, as Spec said, it's an industry standard. One example of this is that all of the content that we currently distribute with our software was designed to be run full size, at 30K, with standard Cambridge scanners (or clones). Also the "default settings" found in our software are for 30K. We make the assumption that people will have an ILDA-standard projector with 30K scanners.
Second, along the lines of what Spec said -- if you have standard Cambridge 6800 scanners, or especially clones, they were essentially designed to be operated at 30K. If you operate them at faster than 30K, you will unwittingly be making sacrifices. The servo component selection in the Cambridge CB6580 and several derivatives do not have the phase margin for faster-than-30K operation. Also, usually the mirrors are not thick enough, so you will begin to excite resonances in the system. The result of one or both of these is that there will be overshoots or other undesirable artifacts. These may only show up in certain images. For example, if you take a VERY close look at the DT40 image, you will see some differences. The green square in the center has overshoots on all four corners, and the white lines underneath that look like an "upside-down ground symbol" are a bit twisted, especially the bottom-most line.
(For those who have changed the component selection of the CB6580, making themselves feel better that they didn't copy the Cambridge design, well, sorry but you have most likely only made matters worst.... I have seen this many times.)
Third, also along the lines of what Spec said, if you take this 30K system and tune it faster than 30K, it will be putting in more current for a particular move. This "more current" tends to heat up the scanners faster. If you have Chinese scanners, one thing we have learned on this forum is that the coil is not formed as well, and not bonded as well to the stator. Thus, this is a good way to reduce the life of the overall scanning system...
There are scanners and amp combinations that were specifically designed to operate faster, such as the Cambridge model 6215 and 671xx high power amp. These can operate at the same scan angle as Cambridge model 6800, but with truly twice the speed. In other words, you can take the "Sample rate" sliders in LD2000 and move them up to 60K, and play them back on these scanners with no other changes to the imagery. No additional points need to be added.
As I said in another post, if you want to scan twice as fast, you must do your job four times as good, because there is a "square law" in the formula which dictates power required to do this. In the case of the Cambridge model 6215, the thermal conductivity is four times as high as it is on a 6800 and 6210. This, along with other factors are what allows the system to scan at 60K. Anyway, it just isn't very wise to take a motor system that was designed to operate at 30K, and operate it faster.
If we have a pre-SELEM meeting in or around Pangolin, I will invite you to check out our "scanner lab", where we build scanners for industrial and military applications. I will also show you software we wrote which accurately predicts the coil resistance and inductance, torque, inertia and other properties of scanners. Rest assured that if I make a recommendation, it is made from a position of knowledge, and not just another opinion...
Best regards,
William Benner